Methylenetetrahydrofolate reductase polymorphisms as risk factors for retinal venous occlusive disease: A literature review

Association of PON1, APOE and SDF-1 Gene Polymorphisms with Treatment Response to Intravitreal Anti-VEGF Treatment in Patients with Retinal Vein Occlusion

PURPOSE

The purpose of this study was to determine whether specific genetic polymorphisms affect the response to intravitreal anti-vascular endothelial growth factor (anti-VEGF) treatment in patients with macular oedema secondary to retinal vein occlusion (RVO).

METHODS

Participants in this prospective study were 50 patients with macular oedema secondary to RVO, who were treated with intravitreal ranibizumab or aflibercept, and were followed-up for 12 months after initiation of treatment. Five single nucleotide polymorphisms (SNPs) from three different genes (APOE, PON1, SDF-1) were examined as potential predictors for treatment response to intravitreal anti-VEGF agents.

RESULTS

Patients with the LL genotype of the PON1 L55M SNP had significantly higher reduction in central subfield thickness (CST) at month 12 after initiation of intravitreal anti-VEGF treatment (101.63 ± 56.80 μm in LL vs. 72.44 ± 39.41 μm in LM vs. 40.25 ± 19.33 μm in MM, p = .026). Patients with the M allele of the PON1 L55M SNP were significantly associated with lower reduction in CST compared to non-carriers (68.29 ± 38.77 μm in LM + MM vs. 101.63 ± 56.80 μm in LL, p = .032).

CONCLUSION

PON1 L55M SNP may serve as a promising genetic biomarker for predicting response to intravitreal anti-VEGF treatment in patients with macular oedema due to RVO.

Case series of retinal vein occlusions showing early recovery using oral l-methylfolate

This case series describes the aggregate rate of recovery in five consecutive subjects (six eyes) with retinal vein occlusion (RVO) who received l-methylfolate and other vitamins via Ocufolin®, a medical food. Subjects were followed for 10-33 months by a single ophthalmologist. Ocufolin® was prescribed at the time of diagnosis and subjects remained on the regimen throughout the time of observation. Examinations were performed in an un-masked fashion at 3-month intervals with recording of best corrected visual acuity (BCVA), average retinal nerve fiber layer (ARNFL) and central macular thickness (CMT), and fundus (examination of the retina, macula, optic nerve, and vessels) photography. Testing was done for vitamin deficiencies, vascular and coagulable risk factors, and methylenetetrahydrofolate reductase (MTHFR) polymorphisms. Vitamin deficiencies and vascular risk factors were found in all subjects, and all four tested subjects carried at least one MTHFR polymorphism. By the end of the study period BCVA in all subjects was 20/25 or better. Cystoid macular edema was identified and measured by optical coherence tomography (OCT). The percent change was calculated and plotted at 3-month intervals using the percent change in thickness from the time of diagnosis and percent change toward normative values for ARNFL and CMT. The total reduction in thickness of ARNFL and CMT from time of diagnosis was 44.19% and 30.27%, respectively. The comparison to normative data shows a reduction of ARNFL from 164.2% to 94% and CMT from 154.4% to 112.7% of normal thickness (100%). Plots showed the aggregate recovery was most rapid over the first 3 months and slowed over the next 3 months with most of the recovery taking place within 6 months of treatment. The rate of improvement in BCVA and resolution of retinal thickening was found to be better than predicted on historical grounds. No subjects progressed from nonischemic to ischemic RVO. Vitamin deficiencies, vascular risk factors, and genetic predisposition to oxidative stress were common in this RVO series. It appears that addressing these factors with Ocufolin® had a salutary effect on recovery.

Acute Macular Neuroretinopathy Associated With COVID-19 Infection: Is Double Heterozygous Methylenetetrahydrofolate Reductase (MTHFR) Mutation an Underlying Risk Factor?

The goal of this report is to present a case of coronavirus disease 2019 (COVID-19)-associated acute macular neuroretinopathy (AMN) with an underlying MTHFR mutation. A 36-year-old male presented to the emergency department with a sudden-onset paracentral scotoma in his left eye. Although optical coherence tomography (OCT) was normal initially, four days later, it revealed a hyperreflective band in the outer plexiform layer with disruption of the ellipsoid zone/interdigitation zone. On infrared imaging and en-face OCT, wedge-shaped lesions were detected around the fovea with their tip oriented toward the fovea. OCT angiography, fundus autofluorescence, fundus fluorescein angiography, and visual fields were performed. The patient was positive for COVID-19 infection. The absence of medical history and the negative results of blood tests led to a diagnosis of AMN associated with COVID-19. Genetic testing for coagulation disorders was scheduled and revealed a heterozygous mutation for MTHFR C677T and A1298C. This is the first case of AMN in a patient with COVID-19 infection and a double heterozygous mutation of the MTHFR gene. Infection is the most commonly reported association of AMN, while MTHFR mutation may represent an additional underlying risk factor. Microthrombosis and small-vessel occlusion are thought to be involved in the pathophysiology of AMN, and patients should be tested for COVID-19 because it may be the first manifestation of the infection.

Inner retinal layer ischemia and vision loss after COVID-19 infection: A case report

Introduction: COVID-19 infection may also occur with ocular manifestations. Paracentral acute middle maculopathy(PAMM) is a condition that causes ischemia in the inner retinal layers characterized by disruptions in capillary plexus flow. Also, ischemia in inner retinal layers secondary to COVID-19 infection has not yet been reported.

Case report: The case, presented with the complaint of gradually decreasing visual acuity in the right eye after COVID-19 infection. PAMM was suspected, however, ischemia was detected in all inner retinal layers with Optical coherence tomography angiography.

Discussion: We showed that it should be kept in mind that atypical retinal involvement of COVID-19 infection could present, with this case.